The supermoon, poised to occur within hours from now, will be the brightest full moon since it appeared almost 70 years ago in 1948. It is a rare sight when the moon is at its fullest size and becomes closest to earth.

Earth's moon is about 238,900 miles away, according to scientists. But on November 13, they say, the moon's distance to earth is estimated to be 221,524 milers. The supermoon watching is a spectacular phenomenon to skilled stargazers.

The November 13 supermoon is said to be one among the three supermoons that will appear in 2016. A second one is due on December 14. Tonight’s supermoon is also called the Beaver Moon.

"This one is historically close," said NASA scientist Noah Petro. "The moon hasn't been this close to Earth since January of 1948." The space between Earth and the moon will still be vast — a height of about 28 Earths.

Petro says an ordinary watcher may not notice the difference in brightness, but regular observers of the moon are expected appreciate the "difference in size of the moon as it goes in its orbit around Earth".

"Find a clear space where you're free, certainly of bright lights, but even [of] tall buildings or trees that will obstruct your view, especially when the moon is low in the sky. Later on at night, when the moon is high in the sky, any spot is going to be fine."

November 2034 will be the next time the moon will be this close to Earth, according to the NASA scientist. The point on the moon's orbit closest to Earth is called perigee and the point farthest away is apogee.

The technical term for a Supermoon is perigee-syzygy of the Earth-Moon-Sun system. In astronomy, the term syzygy refers to the straight-line configuration of three celestial bodies.

The tides on Earth are mostly generated by the moon’s gravitational pull from one side of Earth to the other. The moon’s gravity can result in small ebbs and flows in the continents called land tides or solid Earth tides.